Central Bureau for Astronomical Telegrams
IAUC 6220: C/1995 O1
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Circular No. 6220
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
BMARSDEN@CFA.HARVARD.EDU or DGREEN@CFA.HARVARD.EDU (science)
Phone 617-495-7244/7440/7444 (for emergency use only)
COMET C/1995 O1 (HALE-BOPP)
A. Fitzsimmons and M. Cartwright, Queen's University of
Belfast, have observed the inner jet (IAUC 6216) in R-band CCD
images with the 1-m Jacobus Kapteyn Telescope on La Palma; the jet
appears nearly linear out to 3" from the nucleus, then turns
sharply north. They see no significant change in p.a. (measured
from the center of light to the turn) during Aug. 24.90 and 28.90
UT (305 deg) and Aug. 25.93, 26.92, and 27.96 (315 deg).
M. Kidger, M. Serra, and R. Casas, Instituto de Astrofisica de
Canarias, report monitoring of the spiral-arm feature on Aug. 25
(2.5 hr in R), 27 (2.0 hr in R), and 28 (2.25 hr in B) with the
0.82-m IAC-80 Telescope at Teide Observatory: "The position angle
(280 deg) was as reported on IAUC 6216. No evidence is found for
significant rotation of the base of the jet; these and observations
on Aug. 31 show that the base oscillates by a maximum of 20-30 deg,
suggesting that the jet emanates from a point close to the pole of
the nucleus (within 10-15 deg latitude) and that the comet is
traveling very close to pole-first. The arm extends considerably
farther on Aug. 28 than on Aug. 25, wrapping round to p.a. 0 deg on
Aug. 25, 15 deg on Aug. 27, and 25 deg on Aug. 28. Significant
changes were seen in the jet structure between Aug. 28.88 and 28.97,
the distance between the nucleus and the end of the jet increasing
from about 8" to about 10", while the p.a. of the end of the jet
remained constant. On Aug. 31, the jet was much fainter (and,
where it emerges from the nucleus, more tightly collimated)."
R. M. West, European Southern Observatory (ESO), writes: "E.
Molinari (Osservatorio Astronomico di Brera) obtained 5-min
exposures with the Danish 1.5-m telescope (+ multi-mode DFOSC) at
La Silla on Aug. 31.06 (Gunn i filter; seeing 0".8) and Sept. 1.06
UT (Gunn r filter; 1".0); see
http://www.eso.org/comet-hale-bopp/comet-hale-bopp.html. On both
frames, the northwestern jet is well resolved and, following image
processing of these frames by H.-U. Kaeufl (ESO-Garching), its
structure may be described as follows: On the i frame, the jet
emerges at 3" in p.a. 295 deg relative to the point of maximum
intensity. From there, it curves toward the north to a point about
7" in p.a. 315 deg, where it bends rather sharply about 90 deg
toward the northeast, widens to FWHM about 8", and continues in
direction p.a. about 40 deg over a distance of about 10". The
spatial structure may be helical. A comparison of the two frames
reveals no significant differences (on the r frame, the jet emerges
at 3".5 in p.a. 293 deg) and these images resemble those from
Hawaii and Teide, now also displayed on the WWW. Thus, no obvious
rotational effects can be perceived from these data."
1995 September 1 (6220) Daniel W. E. Green
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